River Boyne Water Quality Management Plan - EPA

River Boyne Water Quality Managmml PlanmFaecal Colijorn~sChloridemChen~ical Oxygen Denland (COD)Bioclremical Oxygen DenlandBOD is a measure of the biological activity of the water. When organic matter is discharged to ariver, it serves as a food source for the bacteria present and is broken down to simple compounds suchas carbon dioxide and water. The amount of oxygen required in this breakdown is known as theoxygen demand. The five day BOD test, (BODg) which is the standard analytical procedure, is theamount of dissolved oxygen taken up by bacteria in degrading oxidisable matter in the sample,measured after five days incubation in the dark at 20 deg.C. The resulting drop in dissolved oxygenis the BOD of the sample. BOD is expressed in mgll of 02 and the standard forsalmonid waters isless than or equal to 5mgil Oz. There is no health significance to BOD but it is a very importantparameter as it gives an indication of the amount of organic matter in the waterbody.Dissolved OqgmAn unpolluted water will be saturated with oxygen and in cent ratio^^ of 9.2mgll represents 100%saturation at 20 deg.C. Oxygen solubility has an iR,w7sr ... ltionship with temperature and therefore